Systems exist that allow a user to remotely start a vehicle. Such remote starting devices are frequently used by persons in hot or cold climates to cool or preheat the passenger compartment. One of the problems associated with these remote starting systems was that the vehicle is vulnerable to operation by unauthorized users. Many of the existing patents in this area of endeavor are directed to preventing unauthorized use of the remotely started vehicle.
The prior art does not appear to address situations where a vehicle is used for maintenance or some other form of work, such as work performed by workmen outside the vehicle, which may require periods where the vehicle must be left running but unoccupied. For example, some utility maintenance trucks have a bucket lift for lifting a workman to perform maintenance, the operation of which may require the engine to be running to provide the electrical or hydraulic power to the bucket lift. In addition, the workmen may need to exit the maintenance truck to inspect a work site. At times like this, it is inconvenient to repeatedly turn off and turn on the vehicle using the key switch and waste fuel by restarting the engine at each stop. In these situations, if the vehicle is left operating, the ignition key must be in the ignition key switch and switched to the ON position. When the vehicle is in this state, it is vulnerable to unauthorized or inadvertent use.
Examples of attempts to provide such a system include U.S. Pat. No. 4,403,675 to Cardwell, U.S. Pat. No. 4,754,838 to Cody, U.S. Pat. No. 5,115,145 to Westberg et al., U.S. Pat. No. 5,180,924 to Rudisel, and U.S. Pat. No. 5,670,831 to Georgiades. These systems use a single relay to prevent unauthorized use when a vehicle engine is operating and the ignition key is removed.
Other examples of attempts to provide such a system include a keyless engine controlling unit, U.S. Patent Application Publication US 2003/0137195 to Suzuki. In the disclosed system, the locked state of the door lock switch for operating the door lock, in particular, the driver's seat side door lock, state is detected. The disclosed system detects the number of times the driver's side door lock switch is turned on and off.